Acid-Insoluble Substances in Reduced Iron Powder from Ores

Abstract:

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X-ray analysis on iron ores and reduced iron powders revealed that around 60% acidinsoluble
substances were hexagonal and tetragonal quartz, another 40% substances were
sillimanite, alumina-silicate, an unnamed zeolite, all contained Si and Al. SEM images displayed
that the particle size of them was in the range of 3~7 μm, which may be the initial source of the
cracking in the sintered body. Statistics analysis showed that the Acid-Insoluble Content (AIC) for
high-grade magnetite powder was (0.130±0.010) % during the latest five months. The predicting
value for reduced iron powder from ore powders should be 0.179 %. However, the testing value for
reduced iron powder was (0.192±0.014) %. The limited difference of 0.013% might imply rare
pollution coming from the reduction and milling processes. The most important step for control
AIC should be the separation process of iron ore powders.

Abstract: Bioactive composite coatings containing sub-layer and working-layer with different
ingredients were prepared using subsonic thermal spraying technology and then heat-treated at 700°C for 1h. Two types of bioglasses, named BG1 and BG2, and Y2O3 were used as additives of the sublayer and working layer respectively. Phase transformation and structure changes of the coatings were investigated
with XRD, DSC and SEM. Results showed that the phases of as-sprayed Ti/BG1 sub-layer were TiN, TiO2 (rutile and anatase), etc. Post-heat treatment changed the phase composition. TiN and anatase transformed into rutile and some new phases generated, which often enriched at pores and cracks. In the working-layer, part of nano-hydroxyapatite powders decomposed during coating preparation. Y2O3
impaired the decomposition to some extent and BG2 enhanced greatly. Post-heat treatment increased the crystallinity of all coatings effectively. The analysis of TG-DSC showed that BG2 added in working-layer crystallized at 700°

Abstract: Monodispersed Cu powders were prepared in aqueous solution through a wet-reduction
process with hydrazine hydrate (N2H4·H2O). In particular, the effect of the dispersant such as sodium
pyrophosphate decahydrate (Na4O7P2·10H2O), carboxymethyl cellulose sodium salt (CMC) in water
solvent on the particle size for the prepared Cu powders was investigated. The Cu powders essentially
were monodispersed and irregular in shape regardless of reaction temperature and dispersant. In the case
of adding the Na4O7P2·10H2O, the particle size of Cu powders increased with the increase of reaction
temperature, which the particles were agglomerated in irregular shape and became to be large. The
particle size distributions was asymmetry and to be broad regardless of reaction temperature. On the other
hand, when the CMC was added, the particle size of Cu powders, which were much finer compared with
adding the Na4O7P2·10H2O as a dispersant, was not much changed with reaction temperature. The particle
size distribution of Cu powder was much narrow regardless of reaction temperature. As a result, it would
be suggested that the CMC was more effective dispersant reagent to produce the monodispersed and fine
Cu powders with narrow size distribution using the wet chemical reduction process

Abstract: Porous calcia stabilized zirconia ceramics (CSZC) with closed pores were presurelessly sintered by adding different contents of zirconia hollow balls. CSZC FGM with porosity gradient structure was then fabricated by laminating five layers with designed contents of zirconia hollow balls. The porosity, microstructure, and bending strength of the obtained CSZC samples were characterized. The results show that the hollow balls distribute uniformly and are well bonded with the matrix, and the porous structure is mainly composed of closed pores. The porosity of the CSZC increases linearly from 5.7 % to 31.6 % when the content of zirconia hollow balls increases from 0 % to 30 %, and the bending strength decreases rapidly from 297 MPa to 30 MPa. The thermal shock behavior of the CSZC and FGM was evaluated using air-quenching technique. It is shown that the residual bending strength of the quenched samples increases after several quenching cycles, and the samples are damaged by thermal shock after eight thermal cycles because of the production of monoclinic zirconia. FGM samples with porosity gradient structure can endure above twelve thermal shock cycles and exhibits better thermal shock resistance.

Abstract: To study the characterization of ursolic acid (UA) and β- cyclodextrin(β-CD) inclusion complex which prepared by ultra-high pressure method. Inclusion complex of UA /β-CD was prepared at 100MPa and 500MPa. The inclusion complex was characterized by IR spectra, X-ray diffraction, Differential scanning calorimetry and Scanning electron microscope. It was testified that the inclusion complex was formed between β-CD and UA at ultra-high pressure conditions.

Abstract: Sodium hexatitanate (Na2O•6TiO2) whiskers with an average diameter and aspect ratio of 1-3 µm and 10-20 respectively were synthesized by calcinating mixtures of industrial grade sodium carbonate (Na2CO3), anatase TiO2 and potassium fluoride (KF). The growth of sodium hexatitanate whiskers was obtainable in a range of TiO2/Na2CO3 molar ratio from 4 to 6, heating temperature from 940 °C to 1000 °C and content of KF from 5 wt.% to 7 wt.% with different morphologies and aspect ratio of the products. The role of KF on the growth behavior of Na2O•6TiO2 whiskers was demonstrated by structural and morphological observation.